Even with increased structural integrity there are still inefficiencies in regards to the transportation of oxygen and nutrients due to diffusion rates. That is, unless CNT muscle tissue does not require as much oxygen for energy production or uses some anaerobic source not available to natural tissues.

Don't know anything about CNT actually. Or what a UG is.

[Technology from another universe. It certainly sounds fascinating in concept.]

Sounds like there's no hurry to get it figured out at least.